1. Technical Field
The present invention relates to an inkjet printer and a printing method.
2. Related Art
A printer is defined as an output device that provides a hard copy record of data as a main form for a discrete graphic character string belonging to one or plurality of predetermined character sets (JIS X0012-1990). In many cases, the printer can be used as a plotter.
The plotter is defined as an output device that directly provides hard copy record of data in a form of two-dimension drawing in a removable medium (JIS X0012-1990).
An inkjet printer is defined as a nonimpact printer, and characters are formed on a paper by ejecting ink particles or small ink droplets (JIS X0012-1990). It is a form of dot printer, and characters or images expressed by a plurality of dots formed by ejecting the ink particles or the small ink droplets are printed.
In the inkjet printer, there is a case that a dot omission occurs when the ink from nozzles is not ejected due to a clogging, etc., or when the ink is not ejected in a proper trajectory. Here, the dot omission is defined as the occurrence of the deterioration of image quality since the halftone dots are not printed in a proper position and a space between halftone dots are expanded. Also, in the field of inkjet printer, the clogging is a phenomenon that an ink ejecting hole of a head is clogged in the inkjet printer (JIS Z8123-1:2013). Hereinafter, the aforementioned ink ejecting hole or ejecting hole is referred to as a nozzle. Further, it discloses that a nozzle that does not eject the ink or does not eject the ink in a proper trajectory is referred to as a defective nozzle.
Further, the halftone is defined as an image formed by dots in number of screen lines, sizes, shapes, or different densities. The halftone is generated by dithering, error diffusion, etc. The halftone dot is defined as an individual element configuring a gradation. As a halftone dot, various shapes such as a square shape, circular shape, oval shape, etc. may be formed. Hereinafter, it discloses that the halftone dot is simply referred to as dot.
The invention that makes a dot omission less noticeable by controlling positions of dots surrounding a portion where a dot omission occurs is disclosed (e.g., see Japanese Laid-open Patent Application Publication No. 2006-173929).